Field of Invention
The present disclosure relates to a planetary gear train for transmission of e-bike motor.
Background
The pedal cycle may be, for example, a conventional pedal cycle in which drive is only ever provided by a cyclist applying force to the pedals thereof, such cycles sometimes being referred to as “push bikes”.
Recently, the pedal cycle has evolved to, for example, a pedelec, an EAPC (electrically-assisted pedal cycle) an electric bicycle or an e-bike. The electrically-assisted pedal cycle (EAPC) or an e-bike is operated by a motor in such a manner that electrical power is used to assist the efforts of a cyclist pedaling the cycle.
Several methods of arranging a motor have been attempted and a recent method is to embed a motor and a transmission inside a hub forming a front wheel or a rear wheel. The hub is integrally formed with the motor and the transmission therein.
The hub includes a hub housing and a stationary shaft. The motor is arranged inside the hub housing, and the stationary shaft is fixed to a front wheel or a rear wheel of a frame of an e-bike or an e-scooter. As a result, the hub housing is rotated relative to the stationary shaft to rotate a wheel of the bike coupled to the hub housing.
The motor is housed inside the hub housing to rotate a rotation shaft by means of the electromagnetic interaction. The motor housing of the motor is fixed relative to the hub housing, and the rotation shaft rotatively arranged in the center of the motor housing transmits a turning effect to a sun gear integrally formed at a distal end thereof, whereby a power is supplied to a transmission including the sun gear.
The transmission is provided with a planetary gear meshed with the sun gear, a margin of the transmission is arranged with a ring gear to mesh with the planetary gear, whereby the transmission receives the turning effect of the rotation shaft in a reduced speed.
Generally, four planetary gears are provided in a pair and rotatably mounted on a carrier to form a planetary gear train. The planetary gear train is formed in such a manner that four planetary gears are rotatably and respectively mounted on a one-bodied carrier using bearings, washers and fixing pins formed on upper and bottom surfaces of the bearing, and a stopper is formed at one surface of the carrier to prevent the respective fixing pins from axially being displaced. Thus, the planetary gear module needs a total of 22 parts including one carrier, one stopper, four planetary gears, bearings, pins and eight washers.
Meanwhile, problems frequently occur in which a washer is lost in the course of coupling the bearings to pins in the assembly process, or the assembly process is advanced with the washer missing due to mistake by an operator, and if the washer is missing in the assembly process, problems may occur in which the fixing pin is detached when deformation is generated by external force.
Another problem is that a manufacturing cost of the one-bodied carrier is very high due to complicated processing method, and the one-bodied carrier cannot be manufactured through a relatively inexpensive sintering or die casting process.